I'm no authority, but I would guess $300-500 undeveloped
End user could of course pay a lot more. I'm surprised that the .us hasn't done better in general. It's nice and short, country code for all those "God Save America" folk...
...
If I was the NFL I would have snapped up that domain when .US was launched.
...Good luck and God Save The World
(btw I still have exfootballers.com - if anyone's interested
)